With increased attention and regulatory resources being directed to the establishment and maintenance of uncontaminated rivers, lakes, and groundwater, it has become imperative for the producer of wastewater to employ a treatment system which avoids the introduction of prohibited levels of contaminants into the surroundings.
In many states groundwater control regulations of exacting strictness have been enacted. Commonly, these regulations require the immediate report of and remediation of any discharges of organic and inorganic wastes, soluble heavy metals, petroleum products, or bacterialogically contaminated materials, which exceed regulatory levels. Although it is always an option to transport the contaminated wastewater to an off-site authorized disposal facility, such transportation is in most circumstances prohibitively expensive due to the large volume of wastewater involved. Furthermore, transportation of wastes deemed "hazardous" may require prior authorization and permitting from regulatory authorities. Rural, residential and agribusiness sources of wastewater are particularly in need of effective treatment systems. Wastewater generators which are not connected with City sewage must independently arrange for disposal of wastewater. For individual and small business wastewater producers, it is essential that the wastewater treatment system be compact and low cost to operate.
Wastewater may contain human wastes, cooking wastes including grease and animal matter, petroleum products, pesticides, lead based paints, and any number of other wastes which are typically associated with water through common cleaning and waste disposal processes. These wastes are typically high in their biochemical oxygen demand (BOD), and their suspended solids (SS) levels.
Known systems have introduced oxidants, in particular ozone, into wastewater. This ozone injection causes inorganic contaminants to oxidize to less soluble oxides and converts organic components to carbonaceous residues and carbon dioxide. Known apparatus has utilized ozone injectors and other equipment involving pressure and velocity changes of wastewater streams to introduce the ozone in the form of a vast quantity of microscopic bubbles. The ozone bubbles tend to form about suspended solid particles and float those particles to the surface of a body of liquid. Clarifiers have been conventionally used which collect the floated solids from the water surface and separate the solids from the wastewater. To achieve higher levels of contaminant removal, wastewater systems have been employed which recirculate all or a portion of the treated wastewater through repeated cycles of ozone injection and clarification.
It has long been known that bacterial impurities may be eliminated by exposure to ultraviolet radiation. Ultraviolet light sources adapted for in-line use within fluid treatment systems are readily available. These UV sources are positioned within the system to expose the effluent prior to its exit from the system. Common ozone generators utilize an electric arc. Thus ozone generation presents significant demands for electric power and hence increases the cost of wastewater treatment.
What is needed is a wastewater treatment system which may be economically employed by small to medium users, and which effectively eliminates objectionable quantities of contaminants from wastewater such that system effluents may be freely disposed of.